Method of removing carbon from metallic filaments.



I UNITED STATES PATENT OFFICE.

WERNER VON BOLTON, OF GHARLOTTENBURG, GERMANY, ASSIGNOR TO SIEMENS & HALSKE, I A. G., OF BERLIN, GERMANY, A. CORPORATION OF GERMANY.

METHOD OF REMOVING CARBON FROM METALLIC FILAMENTS.

. To all whom it may concern: 7

Be it known that I, WERNER VON BOLTON, a subject of the Czar of Russia, and residingat Charlottenburg, near Berlin, Germany, have invented a certain new and useful Method of Removing Carbon from Metallic Filaments, of which the following is a speci-- The present invention relates to the manufacture of electric incandescent lamps, and an important object is to provide a articularly' simple and certain method 0 removing carbon from metallic filaments containing the same.

-difliculties of many kinds. Either the filanients were themselves severely attacked, or-

tlfemethod employed was troublesome and expensive. In accordance with the present invention, on the contrary, the carbon can ';;'be. r emoved very quickly and sim'plywhen the-filament is made incandescent in acetic acid v a ors. Preferably the' filament, attached o electrodes, is brought into the receiver of. an air-pump, and a small basin containing glacial acetic acid is simultaneously placed in the receiver, or the receiver is connected through a tube with a receptacle containing-1 glacial acetic acid. Afters sufficiently jiii fect vacuum has been' I Specification of Letterslatent.

Application filed June 2, 1908. Serial No. 436,270.

Patented Dec. 1, 1908.

made, the glacial acetic acid evaporates, and if the filament is now made incandescent by passing an electric current through it carbon is rapidly removed from it.

What I claim as my invention and desire to secure by Letters Patent is:

1. Method of removing carbon from metallic filaments consisting in highly heating the filament containing carbon in an atmosphere of acetic acid vapors.

2. Method of removing carbon from metallic filaments consisting in highly electricallv heating the filament contaming carbon in an atmosphere ofacetic acid va ors.

3, Method of removing carbon :11

.metallic filaments consisting in passing an electric current through and heating the filament containing carbon to incandescence in an atmosphere of acetic acid vapors.

4. Method of removing carbon from metallic filaments consisting in placing the filament containing carbon in the receiver of anair-pump which; is connected with a receptacle containing glacial acetic acid, in diminishing the pressure in the receiver by means of the air-pump wherebythe acetic acid is vaporized, and in heating the filamerit to incandescence in the vapors of acetic ac1 In testimony whereof I have signed my name to this specification in the presence of two witnesses.

WERNER VON BOLTON.

Witnesses HENRY HASPER, VVOLDEMAR HAnr'r. 

